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Last active April 5, 2020 20:11
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rustc binary bloat from `#[track_caller]`
Raw
config.toml
[llvm]
assertions = true
ninja = true
[build]
docs = false
low-priority = true
[rust]
debug-assertions = true
debuginfo-level = 1
verify-llvm-ir = true
Raw
instrumentation.diff
diff --git i/src/librustc_codegen_llvm/common.rs w/src/librustc_codegen_llvm/common.rs
index 1415fedf11a..6d7f1197919 100644
--- i/src/librustc_codegen_llvm/common.rs
+++ w/src/librustc_codegen_llvm/common.rs
@@ -12,6 +12,7 @@ use crate::value::Value;
use rustc_ast::ast::Mutability;
use rustc_codegen_ssa::mir::place::PlaceRef;
use rustc_codegen_ssa::traits::*;
+use rustc_data_structures::small_c_str::SmallCStr;
use rustc_middle::bug;
use rustc_middle::mir::interpret::{Allocation, GlobalAlloc, Scalar};
use rustc_middle::ty::layout::TyAndLayout;
@@ -255,6 +256,12 @@ impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
if !self.sess().fewer_names() {
llvm::set_value_name(value, format!("{:?}", ptr.alloc_id).as_bytes());
}
+ if alloc.is_track_caller {
+ unsafe {
+ let buf = SmallCStr::new(".track_caller");
+ llvm::LLVMSetSection(value, buf.as_ptr());
+ }
+ }
value
}
Some(GlobalAlloc::Function(fn_instance)) => self.get_fn_addr(fn_instance),
diff --git i/src/librustc_middle/mir/interpret/allocation.rs w/src/librustc_middle/mir/interpret/allocation.rs
index 8b9f0977485..2d0ee8b21b0 100644
--- i/src/librustc_middle/mir/interpret/allocation.rs
+++ w/src/librustc_middle/mir/interpret/allocation.rs
@@ -37,6 +37,8 @@ pub struct Allocation<Tag = (), Extra = ()> {
/// Also used by codegen to determine if a static should be put into mutable memory,
/// which happens for `static mut` and `static` with interior mutability.
pub mutability: Mutability,
+ /// The requested kind of the allocation. Used by codegen for instrumenting static data sizes.
+ pub is_track_caller: bool,
/// Extra state for the machine.
pub extra: Extra,
}
@@ -98,6 +100,7 @@ impl<Tag> Allocation<Tag> {
size,
align,
mutability: Mutability::Not,
+ is_track_caller: false,
extra: (),
}
}
@@ -114,6 +117,7 @@ impl<Tag> Allocation<Tag> {
size,
align,
mutability: Mutability::Mut,
+ is_track_caller: false,
extra: (),
}
}
@@ -143,6 +147,7 @@ impl Allocation<(), ()> {
undef_mask: self.undef_mask,
align: self.align,
mutability: self.mutability,
+ is_track_caller: false,
extra,
}
}
diff --git i/src/librustc_mir/interpret/memory.rs w/src/librustc_mir/interpret/memory.rs
index 04a927c69a6..65543ebfca3 100644
--- i/src/librustc_mir/interpret/memory.rs
+++ w/src/librustc_mir/interpret/memory.rs
@@ -173,7 +173,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
pub fn allocate_with(
&mut self,
- alloc: Allocation,
+ mut alloc: Allocation,
kind: MemoryKind<M::MemoryKind>,
) -> Pointer<M::PointerTag> {
let id = self.tcx.alloc_map.lock().reserve();
@@ -182,6 +182,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
M::GLOBAL_KIND.map(MemoryKind::Machine),
"dynamically allocating global memory"
);
+ if kind == MemoryKind::CallerLocation {
+ alloc.is_track_caller = true;
+ }
let (alloc, tag) = M::init_allocation_extra(&self.extra, id, Cow::Owned(alloc), Some(kind));
self.alloc_map.insert(id, (kind, alloc.into_owned()));
Pointer::from(id).with_tag(tag)
Raw
SUMMARY.md

Local checkout: cff07db629d

Here's the baseline stage1 size without instrumentation:

rust master *$ > $ llvm-size --format=sysv .\build\x86_64-pc-windows-msvc\stage1\bin\rustc_driver-6bca00ecd48151cb.dll     
.\build\x86_64-pc-windows-msvc\stage1\bin\rustc_driver-6bca00ecd48151cb.dll  :
section         size         addr
.text       93358380   6442455040
.rdata      31787826   6535815168
.data         327168   6567604224
.pdata       3726012   6568206336
.rustc         99696   6571933696
_RDATA           148   6572036096
.reloc        482128   6572040192
Total      129781358

In a stage2 build with instrumentation.diff applied, the .track_caller section is 0.68% of the final binary size:

rust master *$ > $ llvm-size --format=sysv .\build\x86_64-pc-windows-msvc\stage2\bin\rustc_driver-2b6f3871b4cd6007.dll     
.\build\x86_64-pc-windows-msvc\stage2\bin\rustc_driver-2b6f3871b4cd6007.dll  :
section          size         addr
.text        85435900   6442455040
.rdata       30815430   6527893504
.data          327168   6558711808
.pdata        3775608   6559313920
.track_c       829904   6563090432
.rustc          98108   6563921920
_RDATA            148   6564020224
.reloc         487072   6564024320
Total       121769338

Note that the stage2 binary is 93.8% the size of the stage1 binary. I assume the >6% reduction in size between stage1 and stage2 builds is due to changes between beta and the current nightly that are not related to implicit caller location.

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